Can fire help save giant oak trees?

Forest service scientists in Asheville, North Carolina are intentionally setting fires. By comparing growth in the burn zones to the health of untouched areas, they hope to learn more about the declining giant oak population.

TRANSCRIPT

Forest Service scientists in Asheville, North Carolina, are intentionally setting fires.

By comparing growth in the burn zones to the health of untouched areas, they hope to learn more about the declining giant oak population.

Here's the story.

All right, we got our quercus coccinea under 3 -- under .3 We got a quercus prinus 3 to 6.

We got an acer rubrum under 3.

You've got to know your forest to take an inventory of it.

We got a quercus alba under.

And these U.S. Forest Service technicians know what lives in this oak-dominated hardwood ecosystem.

It's part of the Bent Creek Experimental Forest in Asheville.

Amelanchier arborea under.

We have permanent research plots scattered throughout the burn unit, and so, prior to the burn and then again after the burn, our research technicians come in and do a sample of the overstory, as well as the understory or regeneration layer.

So you're going in and counting what's on the ground in that area?

Yes, within a certain area, we are getting information on the species, as well as how they respond in terms of height growth to the treatment.

We got two more quercus coccinea under.

The U.S. Forest Service is experimenting with the reintroduction of a totally natural technique to help manage the oak forests of the southern Appalachian Mountains.

Mother Nature used it extensively before and during the early European settlement of the area.

It's called fire.

We are looking at how prescribed fire affects the hardwood regeneration layer, as well as the overstory layer in these forests.

Forest Service personnel used a controlled burn to clear this area in 2013 and again in 2014.

Technicians made an inventory of what was growing in controlled survey plots before the fire and then at regular intervals after the burn.

They will continue to inventory what is growing in the same survey plots for the next three years.

We are looking at how the oaks respond to the fire, yes.

Yeah, if you look over here, is this a sign of success?

It looks like there are things growing in the forest.

Well, it's way too early to say if fire has benefited oak right now.

This is a red oak.

This has been top-killed by fire, so trees are susceptible to mortality following fire.

But all the hardwood tree species in this forest ecosystem sprout back.

So this oak, which is a red oak, has been top-killed by fire but has sprouted back.

Mm-hmm.

Now, why don't all of the trees burn, I guess?

Is oak a little more able to withstand fire?

Yeah, so some tree species, such as oak, are able to tolerate fire a lot better than some of the other species, like red maple, with a really thin bark.

You can tell the oaks -- they have a thicker bark and they're able to just tolerate the heat better.

Hike through areas of the Bent Creek Forest, and you'll get a better understanding of the Forest Service study.

The area that was burned is more open.

You can spot the burn marks on the oak tree bark.

But that openness means sunlight can reach the ground, encouraging more trees to grow.

It's also a more open area for wildlife.

The reintroduction of fire into these oak-dominating ecosystems is a goal and objective associated with forest management across the southern Appalachians.

Contrast that with the forest area that's been left to grow untouched.

The understory between the tall trees is filled with smaller trees and bushes.

It's very dense.

And while the forest needs both types of habitat, the Forest Service is focusing on oak because the once-dominant species is in decline.

It's got a DBH of 14.5 centimeters.

Oak trees were overharvested for timber and to clear land for farming.

Fire suppression is one possible reason why the oaks haven't bounced back.

Oak trees need fire to clear out the forest floor.

Other possibilities include pests, climate change, which favors other types of trees, and even the increased consumption of acorns and seedlings by growing mammal populations.

In these oak-dominated systems, we're often managing for the oak component, so we're trying to sustain that oak component across the landscape and over time.

We have a variety of tools to accomplish our management objectives.

We can use prescribed fire.

We can use timber harvesting and herbicide.

So we have a variety of tools that we can use to accomplish those specific management objectives.